zero-day

Meanings

1. Of warez, released less than a day after the official product release.
2. Of a vulnerability, newly discovered, and therefore still not fixed and possibly exploited by hackers or other criminals.
3. Of an exploit or its threat or an attack, benefiting from a newly found and yet unpatched or unmitigated flaw in software or hardware; using a zero-day vulnerability.
4. Used other than figuratively or idiomatically: see zero, day.

1. A vulnerability that has been discovered recently, and is yet unpatched or unmitigated; a zero-day vulnerability.
2. A day without obligations, where one does not worry about being productive.